There is already known, for example according to document CH 560 410, a timepiece of the type mentioned above, comprising an hours wheel coupled to the dial train, and a first pipe designated hours pipe bearing in a standard manner an indicating hand. Between such wheel and such pipe is interposed a coupling arrangement which furnishes a clutching/declutching function, while assuring indexing of the indicating hand in the angular positions corresponding to integer fractions of hours.
To this end, the hours pipe includes on the one hand a correction wheel which is controlled by a correction mechanism driven by the stem and, on the other hand, a star, the outer teeth of which cooperate with a driving roller.
Such roller includes a stud engaged in a radial slot formed in the plate of the hours wheel which is borne by a second pipe mounted to rotate on the hours pipe. Such driving roller is additionally maintained within the teeth of the star through a spring wire fixedly maintained on such wheel.
The roller may thus be driven in rotation by the hours wheel and it can, in normal operation thanks to its cooperation with the teeth of the star, drive the hours pipe which assures clutching between such pipe and said hours wheel.
During passage from one time zone to another, the user acts on the correction wheel thanks to the time setting stem which is then urged into a special position and it may thus effect direct rotation of the hours hand in acting on its pipe. This movement has no influence on the position of the hours wheel since rotation of the star provokes a skipping movement of the rollers by radial displacement of the latter at the exterior of the teeth of the star which assures declutching between the hours pipe and the hours wheel.
Next, the elastic return of the roller into the teeth of the star under action of the spring permits indexing of the hours wheel into a position corresponding to an integer fraction of an hour relative to the preceding position.
In this structure, the hours wheel is formed by the highest wheel or upper wheel (in the use position of the timepiece), while the correction wheel is formed by the lowest wheel which forms thus a lower wheel relative to the preceding.
These functions cannot be inverted. Effectively, should one wish that the lower wheel be the one which forms the hours wheel and the upper wheel, that which forms the correction wheel in order to guard standard gearing plans with the dial train, it is necessary then in such structure that the indicating hand be borne by the second pipe, that is to say, by the outer pipe. This solution necessitates providing a special fitting of the hands and does not permit use of an original hands fitting. This structure from the prior art may thus not be easily adapted to a standard movement.
This is why, in such structure, the hours wheel, in order to be able to mesh with the dial train pinion, includes a relatively thick toothing which necessitates special machining. Additionally, the plate face of the hours wheel must be shaped in order to assure anchoring of the spring which further requires a fitting operation. Thus, this timepiece is costly to make.
Furthermore, there is known from document CH 577 700 a timepiece also permitting an independent correction of the hours wheel, but in which the driving roller cooperates with the interior teeth of a wheel which pivots on a single pipe. Such wheel because of the interior toothing is thus also costly to form and its centering is not effected on a bearing of length sufficient to be reliable.
The present invention thus has as purpose to provide a timepiece of the type mentioned hereinabove which is inexpensive while being capable of adaptation to any type of movement without modifying, the original hand fitting and with a meshing of the lower wheel with the dial train.